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Brachial plexus nerve block

Find out more about the brachial plexus block and why you may need one.

Download a pdf version of this information by following the link on the right.

What is the brachial plexus?

It’s the bundle of nerves that supply your shoulder, arm and hand with feeling and power. These nerves start in your neck and travel via your armpit eventually reaching your hand.

What is a brachial plexus block?

We use it for surgery shoulder, arm, or hand surgery. It’s an injection of local anaesthetic to remove feeling and movement in these areas.

We may put the injection in the side of your neck above or below your collar bone, or in your armpit depending on the operation you have.

Your anaesthetist will discuss the risks and benefits of the procedure. Together you can decide whether a brachial plexus block is best for you.

What are the benefits of a brachial plexus block?

It avoids the risks of a general anaesthetic.

It may be possible to have your operation with a brachial plexus block alone. This may be important if you have heart or breathing problems. You will be awake and pain free during surgery, although you may still feel pressure and movement in the area.

You may have a block as well as a general anaesthetic. It provides pain relief after your operation, which reduces the need for strong pain killers after surgery. It can also help physiotherapy to start moving your arm or hand to help recovery.

A brachial plexus block increases blood flow to the affected area. In certain situations, this may improve healing and speed up your recovery.

What should I do before my operation?

As for a general anaesthetic, we’ll ask you not to eat for 6 hours or drink 2 hours before your operation. This is really important if you’re having a general anaesthetic as well, or if you need one unexpectedly. Your anaesthetist will assess you before your operation and answer any questions you may have.

If your surgery is in the morning

  • Do not eat food after midnight
  • Drink water only until 6am

If your surgery is in the afternoon

  • Do not eat food after 7.30am
  • Drink water only until 11am

What happens during the procedure?

When you arrive in theatre, your anaesthetist will attach equipment to you which monitors your heart rate, blood pressure and oxygen levels. They’ll use a needle to place a cannula (a thin plastic tube) into a vein in your other hand or arm.

We can do the procedure while you’re awake, sedated or anaesthetised.

Firstly we’ll clean the site of injection and use local anaesthetic to numb the skin. We then inject local anaesthetic around the nerves. Initially your arm will feel warm and tingly. Within 40 minutes, it will become numb and heavy.

Your anaesthetist may use an ultrasound machine, or a small electric current to place the needle correctly. The electric current will make your arm twitch which is a strange feeling but should not be painful.

Occasionally your anaesthetist may suggest placing a catheter (very thin plastic tube) through the needle at the same time. This will remain in place next to the nerves after we remove the needle. This means we can give you more local anaesthetic later, up to a few days after your operation.


The effects of the local anaesthetic will last between 4 and 24 hours  (on average about 10 to 12 hours). Your arm will stay in a sling until your strength returns. Please make sure you have full strength and feeling in your arm before you start using it.

Are there any risks ?

It’s a routine procedure performed with maximum regard for your safety. However all medical treatments carry a risk. Your anaesthetist may suggest performing this block to avoid the risk of a general anaesthetic.

Brachial plexus blocks are not always completely effective. Sometimes the local anaesthetic does not spread to all the nerves. The operation you’re having and your general body shape also affects the success rate. Your anaesthetist will be able to tell you how likely the block is to work fully.

If the block does not work sufficiently for your operation, your anaesthetist will use another form of anaesthetic and pain relief before and after surgery.

Risk due to local anaesthetic

Allergy to local anaesthetics can happen. It’s very rare, and less likely than allergies caused by general anaesthetics. Overdose of anaesthetic should not happen because we take your weight into account when calculating how much local anaesthetic you need.

Serious problems are rare but include fits, heart or breathing problems. Your anaesthetist is trained to deal with these emergencies.

Risk to nearby structures

If we put the injection in the side of your neck, side effects can happen including:

  • hoarse voice
  • droopy eyelid
  • feeling faint.

Sometimes you may find taking a deep breath difficult, or breathing more of an effort than normal. All these are temporary and will wear off when the block wears off.

If we inject around the collarbone, there’s a small risk (1 in 1000) of lung damage. We can usually manage this to keep you safe and permanent harm is very rare. Your anaesthetist can tell you more about this.

For all injections, there’s small risk of bleeding due to blood vessel damage. We can treat this by direct compression or providing extra fluids into a vein.

Please tell your anaesthetist if you take any blood thinning medications.

Nerve damage

It can occur because of direct injection into the nerve, bleeding or infection. The risk of permanent nerve damage is rare and it’s the same for all injection sites. The best studies we have suggests nerve damage occurs in 1 in 15,000 to 30,000 patients. This compares to the risk of dying on the UK’s roads, which is also 1 in 15,000 people every year.

Patients commonly notice areas of tingling and/or numbness in the arm, shoulder or hand. This occurs in around 1 in 20 patients and usually resolves within 3 weeks or occasionally, up to 3 months.

Other causes of nerve damage

These are not caused by the brachial plexus block and include:

  • damage caused by the surgery
  • pressure on the nerves while you’re anaesthetised due to awkward positioning
  • use of a tourniquet on your arm during surgery which compresses the nerves and occasionally damages them
  • swelling of the area after your operation
  • other medical problems, for example, diabetes.

More information

If you have any questions please ask your anaesthetist, surgeon, or nurses on the ward.